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New CHOD tests with SiPM readout in Napoli

New CHOD tests with SiPM readout in Napoli. F.Ambrosino , G. Anzivino , P. Cenci, V. Duk , P. Massarotti, M. Mirra, M. Napolitano, M. Piccini. Goals of the test.

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New CHOD tests with SiPM readout in Napoli

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  1. New CHOD tests with SiPMreadout in Napoli F.Ambrosino, G. Anzivino, P. Cenci, V. Duk, P. Massarotti, M. Mirra, M. Napolitano, M. Piccini

  2. Goals of the test • Joint effort from Napoli and Perugia people to test the Mainz prototype with a SiPMreadout and CHANTI electronics to powerSiPMs and amplifysignals • Assessfeasibility, compare (ifpossible) with Mainz results, thus • Use Mainz prototype • Use Mainz trigger system (but w/o CFD…) [manythanks to R. Wanke!] • Tests in Napoli: climaticchamber, experience with SiPM, availability of CHANTI electronics

  3. Test setup • Trigger system: 2 x scintillatorpads w PMT readout. No CFD, discriminatedsignals in AND • 12 +12 fibers detector from Mainz (w BCF-92 1.2 mm round fibers)  actually 11+11 … • SiPM Hamamatsu 50 mm cell, 6 x 6 mm2 w low(1.6 MHz) darkrate (≲ 150 euro each for lowquantityorder) • Dedicatedfibers –SiPMcouplingdesigned and realized in Napoli (L. Roscilli) • Tests in climaticchamber • Readout w 2GHz bandwidth scope 5 Gs/s • Can emulate, in software both CFD and ToT • Chargedetermination to assessNpe • Full signalshape to study rise and falltimes

  4. Mainz prototype (out of the box)

  5. Fibers-SiPMcouplingsystem Prototypeassembled

  6. Response and efficiency • SiPMcharacterized to find 1pe charge≈4 pC • Difficult to estimate precisely due to RF noiseproblems . Uncertaintyat 10-20% level. • Signalsintegrated to obtaintypicalresponse Allevents Q2(pC) Q1(pC)

  7. Response and efficiency • SiPMcharacterized to find 1pe charge≈4 pC • Difficult to estimate precisely due to RF noiseproblems . Uncertaintyat 10-20% level. • Signalsintegrated to obtaintypicalresponse Peakregion Q2(pC) Peakaround 100 pC i.e. >20 pe Q1(pC)

  8. Response and efficiency • SiPM characterized to find 1pe charge ≈4 pC • Difficult to estimate precisely due to RF noise problems . Uncertainty at 10-20% level. • Signals integrated to obtain typical response Low response region Q2(pC) Single «view» trulyinefficientevents≲ 1% 10% faketriggers due to acceptancemismatch Q1(pC)

  9. Acceptanceissues • Dedicatedstudy to betterunderstand trigger problems • Analogsignals from trigger collected • Clear evidence for anticorrelatedsignals: inclinedtrackstouchingmarginallyone of the palettes due to small misalignment (and/or signalsgeneratedinto the light guide) thesewillnot hit the detector • Need to re-run with higher trigger thresholds and bettermechanics to avoidthis [N.B. waiting for PhysicsDepartment to re-open aftersummerclosing! Data wastakenAugust 2-3 and analysedduringfollowingdays…]

  10. Time studies • Correct time walkusing «software» CFD on eachcollectedwaveform. T vs Q raw

  11. Time studies • Correct time walkusing «software» CFD on eachcollectedwaveform. T vs Q software CFD Apparent «early» signaltails due to (late) small trigger signals: remember, no CFD for trigger!

  12. Time resolution (1) • Single viewresolutions • Include trigger jitter • «software» CFD • «Early» tailsvisible s=1.02 (1) ns s=1.03(1) ns

  13. Time resolution (2) • Time differenceamongtwoviews • Trigger jittercancels out • Comparesdriectly to Mainz PMT result (s=1.19 ns) s=1.059 (9) ns • Time average of twoviews • Includes trigger jitter • «Early» tailiscorrelated in bothviews (and thusispresent in the average) becauseis a (common) trigger walkeffect s=0.845(8) ns

  14. Time resolution (preliminary) The full pictureisconsistent with: • Trigger «core» resolutionabout 700 ps (checkedindependently) • Single viewintrinsicresolutionabout 750 ps • Twoviews time averageresolutionabout530 ps • Slightlybetterthan PMT result (butmissingreal CFD electronicsfluctuations) • Handles to improvefurther: • Thickerscintillator (the oneusedis 15 mm thick) • Betternoiseshielding(signalsare amplified 25X…) • Betterfiber-SiPMcoupling (the oneusedisstillpreliminary) • Betterreflectivewrapping of the detector

  15. Efficiencyat high rates SiPMsignalshave a typical «core» with FWHM of O(20-30) ns and a long (>120 ns) tail-> possibleissueat high rates! Howeverdeviceefficiencyisalmostrestoredbefore the tail of the signalis over->see CHANTI presentation for details Here we show onlyone plot obtained with the CHANTI at the BTF: evidence of e≈97% to detect a secondparticlehitting the detector between30 and 80 ns after a first oneisobtained. Assuming 100% inefficiency for first 30 ns and 97% efficiency for remaining 120 ns onegets2% average dead time for a 550kHz rate in a single tile, the long tailcontributing for only 10% to the overall dead time. Eff2(Dt)/ <acceptance> Dt(ns)

  16. Conclusions • Preliminary tests of Mainz prototype with Hamamatsu SiPMreadout compare well with the PMT resultsshowingSiPMs to be a viablesolution for the new CHOD readout • Preliminary results with CHANTI@BTF show that the long tail of the SiPMsignalseemsnot an issueat the maximum ratesforeseen for new CHOD. (butbeware! the SiPMisnot the same…)

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